Doses to patients from routine diagnostic X-ray examinations in England

A collaborative survey between the National Radiological Protection Board and the Hospital Physicists' Association has been conducted to ascertain current levels of exposure for patients undergoing 10 routine types of X-ray examination in England. The main part of this study consisted of measurements on nearly 3200 patients attending 20 randomly selected English hospitals. The energy imparted to each patient was determined from a measurement of the total exposure-area product for the examination. In addition, thermoluminescent dosemeters were attached to the patient's skin to enable the derivation of doses to the major radiosensitive organs, either directly or using appropriate conversion factors calculated for a mathematical phantom by a Monte Carlo technique. Histograms are presented showing the wide distributions often observed in the doses for each type of examination. Mean values of exposure-area product, energy imparted to the patient, entrance skin dose per film and organ dose are reported, together with coefficients of variation. Comparison of the results with those from similar surveys in the UK and abroad is complicated by inconsistencies in the reporting of such data, but substantial differences are sometimes apparent, particularly for the estimates of organ doses. The present measurements will provide a useful baseline for future measurements and will be used to evaluate the collective dose to the population from medical exposures and the radiation risks from the various radiological procedures.     

湖南省X线胸部诊断检查受检者的体表照射量

根据湖南省各种容量x线机及各类医院抽样,通过门诊胸透1934例(男114l侧、女793例),群检胸透适546例(男249例、女297例)、胸片摄影550例(男339例、女211例)受检者的体表照射量测定,得到全省x线胸部诊断检查时受检者的平均体表照射量.门诊胸透一次,受检者参考点处照射量平均值为1.1伦,群检胸透一次为0.7伦,胸片摄影一次为0.07伦.讨论了x线机防护条件对胸透照射量的影响.及胸片摄影条件对照射量的影响.     

Oblique chest film: value in routine and selective use

A retrospective analysis is presented of 308 consecutive cases in which four views of the chest (right and left anterior oblique, posteroanterior, and lateral) were obtained. Most cases (257) were from adult cardiac clinics or thoracic surgery clinics, where the indications were for questionable cardiac abnormality, known cardiac abnormality, or thoracic malignancy. Fewer cases (37) were studied to attempt clarification of possible abnormality on routine films. Of the 257 routine studies, the oblique views yielded no further information in 97.6% of cases, and missed lesions in 1.3%. In the selective group, the oblique views provided information or confirmatory evidence in about 95% of cases when requested by radiologists. The results throw considerable doubt on the value of oblique films in routine studies, but suggest that they may still have a value in delineating possible abnormalities seen on other views or in cases of pleural disease.     

Risk-benefit analysis of 18FDG PET cancer screening

The benefits of (18)F-fluorodeoxyglucose ((18)FDG) positron emission tomography (PET) cancer screening are expected to include a large population of examinees and are intended for a healthy group. Therefore, we attempted to determine the benefit/risk ratio, estimated risk of radiation exposure, and benefit of cancer detection. We used software that embodied the method of the International Commission on Radiological Protection (ICRP) to calculate the average duration of life of radiation exposure. We calculated the lifesaving person years of benefit to be obtained by (18)FDG PET cancer screening detection. We also calculated the benefit/risk ratio using life-shortening and lifesaving person years. According to age, the benefit/risk ratio was more than 1 at 35-39 years old for males and 30-34 years old for females. (18)FDG PET cancer screening also is effective for examinees older than this. A risk-benefit analysis of (18)FDG-PET/computed tomography (CT) cancer screening will be necessary in the future.     

Effective DQE (eDQE) and dose to optimize radiographic technical parameters: a survey of pediatric chest X-ray examinations in Korea

Objective

The purpose of this study was to investigate the effect of various technical parameters for dose optimization in pediatric chest radiological examinations by evaluating effective dose and effective detective quantum efficiency (eDQE).

Materials and methods

For tube voltages ranging from 40 to 90 kV in 10 kV increments at the focus-to-detector distance (FDD) of 100, 110, 120, 150, 180 cm, the eDQE was evaluated at same effective dose.

Results

The eDQE was considerably higher without the use of the grid on equivalent effective dose. This indicates that the reduction of scatter radiation did not compensate for the loss of absorbed effective photons in the grid. The eDQE increased with increasing FDD because of the greater effective modulation transfer function (eMTF) with lower focal spot blurring. However, most of the major hospitals in Korea employed a short FDD of 100 cm with the grid. The entrance surface air kerma values for the hospitals of this survey exceeded the Korean reference level of 100 μGy.

Conclusions

The different reference levels might be appropriate for the same examination conducted on children of different ages. Also, it is necessary to refine the technical parameters to perform pediatric chest examinations.     

Nuclear medicine for general radiologists: endocrinological examinations

We reviewed nuclear endocrinological examinations of the thyroid, parathyroid, and adrenal glands that are clinically performed in Japan as well as somatostatin receptor imaging, which is widely used in Europe, the United States, and other countries. 123I thyroid scintigraphy is especially useful in detecting ectopic goiters and differentiating between Basedow's disease and subacute thyroiditis or Plummer's disease, all of which exhibit thyrotoxicosis. 201Tl is useful to detect foci metastasized from well differentiated thyroid cancer and to differentiate malignant from benign tumors. 67Ga-citrate is an agent used for patients suspected of having malignant lymphoma or undifferentiated carcinoma of the thyroid. Radioiodinated MIBG is a specific agent for medullary thyroid carcinoma. 99mTc-MIBI is a good agent for locating hyperfunctioning parathyroid tissues. 131I-adosterol is useful to locate the lesions of primary aldosteronism, Cushing's syndrome, adrenogenital syndrome, and select adenomas among incidental tumors. Radioiodinated MIBG scintigraphy has high diagnostic accuracy in locating pheochromocytomas and neuroblastomas. 111In-labeled octreotide is useful in locating, hormone-producing gastrointestinal and pancreatic tumors including carcinoids, gastrinomas, and insulinomas. Radiolabeled somatostatin receptor analogs are used not only to locate but also to treat malignant somatostatin receptor-positive tumors. We hope that Octreoscan will be available in Japan in the near future.     

Screening chest X-ray examination with kinetic analysis using flat-panel detector

We are developing dynamic screening radiography to provide kinetic information for lung respiratory examination using a flat-panel-detector (FPD) system. We modified the FPD system (CANON CXDI-22) to take sequential images for a short period of time (10 seconds, 3 frames/sec). Sequential chest radiographs from full inspiration to expiration were taken and analyzed for diaphragm movement and density changes in local lung areas to objectively detect respiratory anomalies. Our methods derived some respiratory functions such as regional air passage and lung structure movement, and suggested that the degree of chronic obstructive pulmonary disease and interstitial pneumonia could be evaluated quantitatively.     

Shoulder MRI: routine examinations using gradient recalled and fat-saturated sequences

Although the signs of complete rotator cuff tears on MRI are well established, tendinitis and partial rotator cuff tears cannot always be readily depicted. In order to optimize the soft-tissue contrast of shoulder imaging without increasing imaging time for routine applications, we compared spin-echo and gradient-echo sequences with and without fat saturation and studied the soft-tissue contrast of spoiled gradient-echo sequences with several different parameters. We conclude, that fat-saturation is not necessary in order to improve the soft-tissue contrast. Successful fat suppression was only achieved in 50% of cases. We found a gradient-echo sequence with a double echo acquisition (echo times TE: 11 and 34 ms) with a long repetition time (TR: 600 ms) and a moderate flip angle (20°) very helpful in diagnosing rotator cuff pathology. Offprint requests to: Harry K. Genant     

肺挫裂伤的CT与X线平片对照分析

目的：探讨肺挫裂伤的CT诊断价值。方法：对26例临床诊断肺挫裂伤的CT与X线平片对照分析。结果：肺内表现：轻度7例，平片阴性3例；中度13例，平片与CT均可见阳性表现；重度6例，其中3例因并发胸腔、胸壁损伤致平片漏诊。结论：CT扫描对肺挫裂伤的诊断准确率明显高于X线平片，是目前诊断肺挫裂伤的最有效手段。     

Correction of respiratory movement using ultrasound for cardiac nuclear medicine examinations: fundamental study using an X-ray TV machine

Organ movements that occur naturally as a result of vital functions such as respiration and heartbeat cause deterioration of image quality in nuclear medicine imaging. Among these movements, respiration has a large effect, but there has been no practical method of correcting for this. In the present study, we examined a method of correction that uses ultrasound images to correct baseline shifts caused by respiration in cardiac nuclear medicine examinations. To evaluate the validity of this method, simulation studies were conducted with an X-ray TV machine instead of a nuclear medicine scanner. The X-ray TV images and ultrasound images were recorded as digital movies and processed with public domain software (Scion Image). Organ movements were detected in the ultrasound images of the subcostal four-chamber view mode using slit regions of interest and were measured on a two-dimensional image coordinate. Then translational shifts were applied to the X-ray TV images to correct these movements by using macro-functions of the software. As a result, respiratory movements of about 20.1 mm were successfully reduced to less than 2.6 mm. We conclude that this correction technique is potentially useful in nuclear medicine cardiology.     

Pneumatosis intestinalis in bone-marrow transplantation patients: diagnosis on routine chest radiographs

We report seven cases of pneumatosis intestinalis that was initially detected on routine chest radiographs made in adult bone-marrow transplantation patients. The cases were collected over a 13-month period. The chest radiographs generally underestimated the extent of the pneumatosis, as subsequently seen on plain abdominal films. However, the portions of bowel most extensively involved were those seen on the chest radiographs (transverse colon, hepatic and splenic flexures, stomach). One patient had pneumoperitoneum also. Pneumatosis developed within 6-293 days after transplantation. The cause of pneumatosis intestinalis was multifactorial. Three patients were asymptomatic. Clinical management of all seven patients was altered because of the detection of pneumatosis. The dose of steroids was increased in three patients to treat graft-vs-host disease, antibiotic drugs were given to three patients for enteric pathogens, and bowel rest was prescribed for one patient with mucosal injury from intense chemotherapy and radiation therapy. These cases show that the chest radiograph makes early diagnosis of pneumatosis intestinalis possible in posttransplantation patients.     

胸部创伤的X线诊断分析

近年来,随着交通及其他意外事故的频繁发生,胸部创伤患者日渐增多。胸部在直接或间接暴力作用下,均可发生损伤的可能。因此,X线检查对其有着重要意义,现将我院近几年来资料完整的胸部创伤患者100例结合文献分析讨论,以期提高对胸部创伤各种影像表现的认识与理解。